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The vulnerability known as CVE-2026-45018 affects MCP integrations within server environments by failing to properly validate user-supplied command strings.
Specifically, the root cause originates in the command validation parsing logic where executable names are checked against configurations.
When an attacker supplies a malicious fullCommand string containing unvalidated arguments alongside allowed executables, the backend executes them.
The lack of strict argument sanitization allows arbitrary command execution through standard input-output transport mechanisms.
Because the affected endpoint can be accessed without prior authentication, remote unauthenticated attackers can leverage this flaw.
The server processes incoming requests via the /mcp endpoint and forwards unsanitized parameters directly to execution functions.
If the configuration allows default fallback values or leaves execution parameters unbound, all restrictions are effectively bypassed.
This enables malicious actors to spawn shell processes directly on the host infrastructure with elevated administrative privileges.
Attack vectors typically involve sending carefully crafted JSON-RPC payloads over network protocols to trigger the flaw.
Once the command payload reaches the parsing layer, the operating system interprets embedded shell metacharacters immediately.
Remediation requires implementing strict allowlists, disabling vulnerable stdio transports, and updating affected software packages.
Security researchers emphasize that zero-click exploit chains can weaponize these input flaws to compromise underlying containers.
Administrators must audit environment configurations, restrict network access boundaries, and enforce proper authentication tokens.
Without timely patching, systems remain entirely exposed to total host compromise and persistent unauthorized data access.
DailyCVE Form:
Platform: Chainlit MCP Server
Version: Below 1.2.0
Vulnerability: Command Injection
Severity: Critical Risk
date: August 25 2026
Prediction: September 1 2026
What Undercode Say:
git clone https://github.com/pete-builds/mcp-threatintel.git cd mcp-threatintel export MCP_THREATINTEL_AUTH_TOKEN=$(openssl rand -hex 32) docker compose up -d
import asyncio
from fastmcp import FastMCP
mcp = FastMCP("ThreatIntel")
@mcp.tool()
async def lookup_ioc(indicator: str) -> str:
return f"Checking indicator: {indicator}"
Exploit: (Educational Purposes!)
curl -s -X POST http://localhost:3707/mcp \
-H "Content-Type: application/json" \
-d '{"jsonrpc": "2.0", "method": "tools/call", "params": {"name": "execute", "arguments": {"command": "id"}}, "id": 1}'
Protection: from this CVE
Disable the vulnerable stdio transport features in the configuration files immediately.
Update all underlying MCP server components to the latest patched stable releases.
Enforce strict bearer token authentication across all active network communication channels.
Restrict network exposure by placing container instances behind secure firewall rules.
Impact:
Successful exploitation grants full remote code execution under the host server process privileges.
Attackers achieve complete loss of confidentiality, integrity, and availability of the system.
Compromised environments face risks of data exfiltration and persistent lateral movement.
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Sources:
Reported By: github.com
Extra Source Hub:
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